Most analysts see PayPal going up against Square not just because of the shape, but because Square is currently processing $11 million in payments per day, and PayPal’s brand recognition makes it a noteworthy contender. Intuit’s cylindrical GoPayment device has lagged behind Square in exposure and profits, but is still in the running. VeriFone’s PAYware Mobile on the other hand is more a sleeve than a dongle, and is tailored for Apple products (iPhone, iPod Touch, iPad).

PayPal Here is squarely going up against Square, with a distinct advantage on the transaction charges front. Intuit GoPayment will be sidelined even more unless it finds a way to drum up more attention and generate user interest. VeriFone announced this month it will integrate the Isis digital wallet platform into its products.

The PayPal Here card reader and merchant app for iPhone are were shipped to select merchants in the United States, Canada, Australia and Hong Kong last week. A general release will be available in these four countries by next month. The Android version will also be released to the same markets next month. PayPal Here will reportedly be available in more countries in the coming months.

*Disclaimer: The author works full time for VeriFone Inc., and is in no way trying to influence anyone’s decision one way or another.